A conventional drivetrain, or powertrain, for machines, particularly for heavy industrial machinery such as machinery used in forestry, landfill operations, agriculture, mining, construction, material handling, tunneling, drilling and other industries, often includes a power source that is operatively connected to ground engaging elements, such as rear wheels of the machine. In particular, for example, the power source may be operatively connected through a transmission to a rear differential that is configured to transmit rotational power to rear wheels disposed on opposing sides of the machine. Two axle shafts extending from the differential may be connected to the rear wheels through drive assemblies, which might each include a final drive. The final drive may be configured to provide a reduction in rotational velocity, and an increase in torque, delivered to the rear wheels.
Final drives have a variety of different configurations, depending on the particular application, and typically include sun gears, planet gears, carriers, and ring gears. Such planetary gear sets are known and, typically, each of the planet gears in the set is rotatably supported on a pin or shaft, which is supported on a respective carrier, using roller or needle bearings. Although capable of reducing friction between rotating components and suitable for some applications, roller-type bearings are known to have low load bearing capacity. In addition, roller-type bearings have numerous parts, which are potential sources of wear and failure.
European Patent Application 2159454 (hereinafter EP '454) discusses problems with using any type of bearing in an interface between an engine's idler gear and idler gear hub. In fact, lubrication and failure issues with respect to bearings are discussed with respect to various applications. The EP '454 reference goes on to teach a replacement of a bearing between the idler gear and idler gear hub with a low friction coating layer, such as a DLC or polymer coating layer, on at least one of the idler gear and the idler gear hub. It should be appreciated that mechanical systems having rotating components, which may include bearings, are used in a variety of different applications. Each of these different applications may have unique requirements, including load capacity requirements, which must be addressed within certain application constraints. As such, there is a continuing need for improvements with respect to rotating components in mechanical systems.
The present disclosure is directed to one or more of the problems or issues set forth above.